Party-line system for automatic telephone-exchanges.



F. ALDENDORFP.

PARTY LINE SYSTEM FOR AUTOMATIC TELEPHONE EXCHANGES. APPLIOATION FILED 00122, 1912.

1,077,185. Patented Oct. 28, 1913.

5 SHEETS-SHEET 1.

to connectors 586 //7 venfor-g A/dehdorf/ L mwmk F. ALDENDORPF.

PARTY LINE SYSTEM FOR AUTOMATIC TELEPHONE EXCHANGES.

APPLIOATIQN FILED 00122, 1912.

Patented Oct. 28, 1913.

6 SHEETS-8HEET 2.

W/lnesses:

F. ALDENDORFP. 'PARTY LINE SYSTEM FOR AUTOMATIC TELEPHONE EXCHANGES.

APPLICATION FILED 001-22, 1912. I 1 077,1 5, I Patented 0012.28, 1913.

6 SHEETS-SHEET 3.

-P. ALDENDORFP. PARTY LINE SYSTEM FOR AUTOMATIC TELEPHONBIEXGHANGES.

AI PLIdATIoN' FILED 00122, 1912.

Patented Oct. 28, 1913.

KWWWI WIMHI F. ALDENDORFF. PARTY LINE SYSTEM FOR AUTOMATIC TELEPHONE- EXCHANGES.

- APPLICATION IILED 00122, 1 912,

Patented Oct, 28, 1913.

6 SHEETS-SHEET 6.

F a: W 581% //7 Vania/ j UNITED STATES PATENT orrron.

FRITZ ALDENDOBFE OF ANTWERP, BELGIUM, ASSIG'NOR TO WEST ERN ELIE ('J'lYEtIC COMPANY, OF NEW YORK, -N. Y., A. CORRORATION' OF ILLINOIS.

PARTY-LINE SYSTEM FOR AUTOMATIC TELEPHONE-EXCHANGES.

i Specification of Letters Patent. Patented Oct, 28; 1913, Application filed October 22, 1912. Serial No. 727,235.

To all whom it may concern:

Be it known that I, FRrrz residing in Antwerp, Belgium, have invented a new and useful Improvement in Party- Line Systems for Automatic Telephone-EX: changes, of which the following-is a specification.

The object of the invention isto provide a method of applying selective ringing current to a party line by ringing current sef lectors that are independent of the connectors or final selectors whichestablish the connection with the wanted line, and which are caused to select the proper kind of ringing current without. any conscious act on the part of the person that is making the connection. To accomplish this the impulses that cause the final selector to pick out the desired group of tens, or units impulses that cause the final selector to connect to the desired linein thepreviously selected tens group or contact row, are made to flow not vonly through the magnets that cause .the selector to pick out the desired line, but also through the magnet of aringing current selector.

In a known system in which ringing current selectors are actuated by the tens or units impulses, part of the final selector structure. As compared with this known construction thearrangement according to my invention by which the ringing current selectors form entirely independent parts ofiers a number "of advantages 2-,

First, it is possible by connecting the actuating magnet of the independent ring ing current selector in parallel to the final selector magnet that causes the selector to pick out the desired group of tens (for example, vertical magnet or vertical relay on the selectors of the Automatic Electric (10., Chicago) or in parallel to the units magnet (for example rotary magnet or rotary re-"' lay) in any existing exchange to adapt the enchange for party line selective ringing without fixin'g new parts to the selector structures. Y

' Second,--n0 change in themanui'acturing processes of any of the various forms of selectors now in use need be made in order to make existing systems suitable for selective ringing.

' Third, in applying this invention a small.

switch having only the same number of ALDENDORFF,

these selectors form a- ;-.-.In. Figure 1 the circuits contacts as there are stations per party linethat isa switch with four contacts for a four party line-is required as a ringing current selector, while in the known system in which the units impulses are made to set the selective member of the rings ing current selector (German Patent No. 224764) 100 special contacts are required on the final selectors. i

Fourth, it is possible to save most of the talking and test circuit contacts on the final selectors by so arranging the circuits that the independent ringing current selector executes a selective movement at each selective impulse while the wipers or brushes of the final selector with which the ringing current selector is associated only move whenever such movement is necessary for connectmg to another party line. In party line systems m'which there are five stat-ions per line this arrangement results in the saving of 80% of the bank contacts and wiring. Besides, the steps that the final selector takes in a known system merely for selecting the kind of ringing current required, but not for selecting another party line, are

dispensed with. Thus each party line appears at one bank contact of the final selector only and not at as many as there are stations in the party line.

Fifth, by employing independent ringing current selectors a small number of them canbe made to supply a comparatively large group of final selectors with ringing current. For instance the ringing current required by 20 final selectors can be supplied 5 ringing current selectors which are connected to the ringing current leads of the final selectors at the proper moment.

My invention is illustrated in the accompanying drawings.

U of a subscribers individual distributing switch are shown. Fig. 2 illustrates the circuits of. a group selector, and Fig. 3 those of a connector or final selector, a ringing current selector (300) also being shown in this figure. Fig. 4. shows diagrammatically the arrangement of the contact arms of a distributing switch. At the end of each insulating body (1) containing the contact arms 301, 302, 303, there is a projection-(2) The purpose of this proj ection is to momentarily close a pair of contacts (304) immediately before the distributing switch, after performing a hunting operation, reaches the normal position in which it is shown in the figure. The purpose of this pair of contacts will become apparent from the description of the operation of the system. Each distributing switch has ten sets of three contacts, 305, 306. 307 each, and these ten contact sets are distributed at equal distances apart over a segment.- of 120 Three sets of contact arms 301, 302, 303 are provided, and are radially displaced with respect to each other by angles of 120. The moment one set of contact arms leaves the last set of bank contacts another set of contact arms reaches the first set of contacts 305, 306, 307. Fig. 5 shows circuits by means of which one or several ringing current selectors 308 or 309 can be brought into connection with one of a group of connectors 310, 311 for long a time as ringing current is required at that connector. In Fig. 6 the circuits are shown which enable the impulses coming from the subscriber and. which usually are used for stepping the contact arms of a connector up to a desired group of contacts to produce the selective movements of a ringing current selector 812. The ringing current selector shown in the figure controls the lifting magnet 313 of the final selector with which it is associated. \Vith the circuits shown in this figure, five vertical or lifting impulses coming from the subscriber would produce five steps of the ringing current selector, and the fifth ringing current generator 315 would be brought into connection with the ringing current lead 816 of the final selector. The five lifting impulses would, however, result in only one impulse being sent through the lifting magnet 313, so that the contact arms of the connector would only be raised one step. The arrangement shown is intended for five-party lines with selective ringing. For twenty lines with five parties each two rows or groups of ten contact sets only would have to be provided on the connector. If a station on a party line that is connected to a set of bank contacts in the first contact row of the connector is to be called, and it' the bell of the desired station is tuned to ring when the ringing current generator 315 is applied. the subscriber would send five vertical impulses. These five impulses would cause the ringing current selector 312 to take five steps so that the ringing current generator 315 is brought into connection with the ringing current lead 316 of the connector. In taking its first step, the ringing current selector 312 by means of a metallic contactpiece 317 moment-arily connects the contacts 318 and 319 and thus sends an im pulse through the lifting magnet 313 of the connector, thus causing the contact arms of the connector to be lifted to the first hori zontal row or group of contacts. If after the live lifting impulses have been sent by the subscriber the contact arms of" the connector are moved around so as to establish connection with the desired party line in the first horizontal row, a ringing current will be sent over the selected party line that will cause the bell of the desired station on that line to ring. it will be seen that the number of sets of bank contacts on the connector is equal to the number of party lines, and not to the number of stations as has been the case in the systems hitherto proposed. Fig. 7 shows diagrammatically a method of conneeting five-party lines to a connector. l i g. 8 shows diagrannnatit-ally the substation apparatus.

The operations involved in the establishment of a connection between the stations of an exchange with distributing switches, first selectors and connectors will now be traced with the aid of Figs. 1, Q, 3 and tl. Second selectors, third selectors, and so forth could be added without departing from the spirit of the invention. It will be assumed that the station 320. Fig. 1 desires to converse with the station 2325 connected with the same party line. The statious 320 to 325 are ordinary stations of the common battery type provided with an impulse transmitter. the impulse transmitter or controller forms no part of this invention it is merely illustrated diagrammatically by contacts I; and c which may be operated manually to interrupt the wires leading to limbs 1 and 2. respectively, of this line. The contact, 7) prior to leaving the 9 contact (Z connected to the limb, 1 engages the groruided contact 0 in order that the energizing circuit for a relay associated with the limb 2 of the line may not be interruliitcd. The structure and operation o't 105 contact (1 is identical to that of 7; and need not be further described. The controllers are also provided with an additional. con

tact device a. which on the rising and dcscending of the swit'hhook momentarily 11o iarths the limb 2 of the party line. When the calling subscriber raises his receiver from the switchhook a circuit is closed at contacts 7 and g over two relays 326. 327

, (Fig. 1). This circuit may be traced from battery 323 through resistance 329, armature contact 180 of relay 330, armature contact 160 of relay 3531, relay 3:26. limb 1' of party line, station 320., limb 2 of party line, relay 327, back contact .161 of relay 331, back contact 181 oi relay 330, wire 1'10, resistance battery 333. The turning magnet of the distributing switch now receives impulses over the following path :-positive pole of battery, front contact 115 of relay 326, turning magnet 334, back contact 100 of test relay 335, back contact 11-l of relay 33G, interrupter 336, minus pole of the has tery. The moment the contact arms of the distributing switch move out of their nor- 1.30

30 traced through the normal switch 337,

' ing circuit circuit at 03. Each time rendered engaged as will be more fully exlained later. The moment the contact arms 340, 341, 342 of the distributingswitch in their rotary movement reach a free trunk leading to a first group selector-that is 5 a trunk, the test wire 343 (Fig. 2) of which is connected through a resistance 344 to the plus pole of the battery, a current will flow through the test relay 335 of the distributing switch from the minus pole of the battery through the winding of the test relay 335, back contact 182, test contact arm .342, test wire 343, contact 183 of oif-normal switch 345, resistance 344 to the plus pole of the battery. The test relay 335 then attracts 25,its armature and opens the circuit of the turning 1nagnet,-334, including the contact 100, so that the contact arms 340, 341, 342 are stopped moving. At the same moment a locking circuit is closed which may be wire 101; front contact and winding of testrelay 335. This lockkeeps the test relay energized until the distributing switch returns to its normal position and causes 'the contacts of the ofi-normal switch 337 to be re-opened;

The energization of the test relay 335 causes the talking wires 346, 347 to be connected to the contact arms 340, 341. The calling sub- 40' scriber now sends the number of impulses required for lifting the contact arms 348, 349, 350 ofthe first selector found by the distributing switch tothe horizontal row of contactsrepresenting the group of subscribers in. which the desired line is contained. These lifting impulses are sent by interrupting at contact 5 the lead to the lifting wire 1 of the calling line the required number of times. thus interrupting the previously described circuit for the relays 326 and 327. Relay 326 is de'e'nergized by each interruption. Relay 327, however, is retained energized by contact 5 engaging the grounded contact 6 prior to breaking the the line relay 326 is deenergized, the lifting magnet 351 of the group selector receives a current impulse that flows from the minus pole of the battery, Fig. 2 through the back contact 185 of an ofi' normal switch 352, winding of lifting magnet 351, uppermost back contact 186 of the test relay 353, wire 354, contact arm 340 of the distributing. switch, front contact 187 of test relay 335, wire 346, wire 102,

hack contact 188 of line relayv 326, plusv pole contact 184 of the offflows through the lifting magnet causes the contact arms 348, 340, 350, to belifted one step. When the first step is taken the lifting off normal switch 345 moves out of its normal position and disconnects the positive pole of the battery that is ordinarily connected to the test wire 343 from this wire, and thus renders the first group selector busy. After the required number of lifting impulses have been imparted by the relay 326 to the lifting magnet 351 of the group selector, the impulse transmitter at the calling station momentarily interrupts the limb 2 and thus de'energizes the relay 327 at the same time the limb 1- 0f the calling line is connected to earth so as to keep the relay 326 energized. -The relay 327 momentarily connectsthe talkingwire 347 to the positive pole of the battery through the wire 103 and the back contact 194, and thus causes an impulse to flow through the turning magnet 356, Fig. 2, the path of which may be traced battery, Fig. 2, through the winding of the turning magnet 356, back contact 189 of the relay 353, right-hand back contact 190 of the rotary off-normal switch 352, back contact 191 of relay 353, talking wire 355, contact arm 341, front contact 193 of relay 335, talking wire 347, wire 103, bottom back contact 194 of relay 327, to the positive pole of the battery. By this impulse flowing through the turning magnet 356 thecontact arms 348, 349, 350 are caused to take a rotary step and the rotary off-normal switch 352 moves into its working position. This.

from the negative pole of the i of the battery. Each current impulse which first rotary step of the contact arms 348, 349, f

350, is an idle stepthat does not bring contact arms into connection with the bank contacts, and its purpose is merelyto cause the rotary off-normal switch 352 to connect the interrupter 357 to the turning magnet 356. This turning magnet now receives current impulses that cause the contact arms348, 349,, 350 to he stepped around until they reach a trunk leading to an idle connector, when a circuit will be established for the test relay 353 as follows: negative pole of thebattery, winding of test relay 353, back contact 196, test contact arm 350, test wire 359, Fig. 3, off-normal. switch 360, resistance 361, to positive pole ofthe battery. h The current in this circuit energizes the test relay 353 which opens the circuit of the turning magnctr356 so'that the contact arms 348, 349, 350 are', caused to stop. The armatures of the test relay arekept locked in their attracted posit on by a locking circuit that includes the -up er contact of the off-normal switch ll urther results of the energization of---ae test'relay 353 are, that the talking wires 354, 355 and the test wire 343 are connected to the contact arms 348, 349, 350 respectively, and that the release magnet 362' ernias is connected to the test wire 3- 123. By causing two further series of impulses to flow over the line the calling subscriber brings about the selective movements of the connector, Fig. 3. The first of these series of impulses causes oscillation of the armatures of the relay 32", and each time the armatures of this relay are released a current flows from the positive pole of the battery through the back contact 138, wire 102, talking wire 3%, contact arm 340, wire 35-1, contact arm 318, wire 362, back contact of relay 36?), lower contact of rotary off-normal switch 379, lifting magnet 378, to the negative pole of 'the battery. These impulses also How through the winding of the turning magnet 380 of the ringing current selector 300 because the magnet is connectcd in parallel with the lifting magnet 378 of the connector. Thus the impulses which cause the contact arms 382, 383, 558i of the connector to be lifted to the desired row of bank contacts also cause the contact arm 385 of the ringing current selector to be turned step by step. Hence, when the contact arms of the connector have been lifted to a certain row of bank contacts the contact arm of the ringin currentselector will hare made connection with the particular kind of ringing current that is adapted to ring the bells of stations of party lines whose numbers correspond with the row of bank contacts to which the contact arms 382, 333, 38% have been raised. The ringing current selector can, of course, be placed at any distance from the connector as it is connected to the connector only by electrical connections. When the first ries of impulses for the first selective moremcnt of the connector has been sent a can rent impulse is sent, over the wire 363 and through the turning magnet 377 of the connector, this impulse flowing from the positive pole of the battery through the back contact 191 of the relay 327, wire 103. wires 3%, 3G3, rotary off-normal switch 375, turning magnet 37? to the negative pole of the battery. This impulse causes the contact arms 382. 383, 33lto take an idle rotary step which. is used to shift the oftnormal switches 375, 379. The second series of impulses for producing the second selective movement of the connector is now caused to flow by the subscriber, and this again produces oscillation of the armature of the relay 326, whereupon impulses flow from the positive pole of the battery through the back contact 133 of the relay 3:26, i es 102, 3-16, 354,362. back contact of relay upper contact of rotary oil-normal switch 9. turning magnet 37? to the negative pole of the battery. These impulses cause the tact arms 332, 383. 33% of the connector be rotated to the set of bank contacts co: spending with the desired station calling line/is rendered busy by the W selected party line. The connection is now established between the calling subscriber and the desired line. As the'station 320 is calling the station 325 connected to the same party line the connector would act as it the line of the desired subscriber were engaged it special. means were not provid d to prevent this.

It has already been pointed out that a normal switch of the distributing switch belonging to the calling line being moved out of its normal position and thus opening the Contact 339, Fig. 1, so as to disconnect the positive pole of the battery from the test wire 336 leading to the connectors, the coi'inection between the test wire 386 and the positive pole of the battery being o ordinarily established through the winding of the relay 330. The busy condition is removed in the case of a station on a party line calling another station on the same party line immediately after the connector is connected to the line by the last impulse sent by the calling station over the limb 2, Fig. 1. This 'auses oscillation of the armatures of the relay 327, and by this means the opened contact 339 of the elf-normal switch 338-, Fig. 1, is momentarily shunted and a current impulse then flows from the 5 positive pole of the battery through the lowermost back contact 194: of the relay 327, through. wire 103. 'wires 347, 355. 363. back contact of relay 365, Fig. 3, Wire 3733, up

per contact of rotary oft-normal switch 375, 00 winding of relay 367 to the negative pole of the battery. The relay 367 new attracts its armature and connects the negative pole of the battery through its contact 113 to the one end of the winding of the test re- 5 lay 365 of the connector, the test relay bein then energized by a current that flows from the negative pole of the battery through the contact 113 of relay 367,b ack contact and winding of relay 365. test cont-act arm 1 0 38%, of connector. test wire 386, Fig. 1. back contact 390 of relay 327, Fig. 1. back contact 403 oil-relay 389, winding of relay 330,

to the positive pole of the battery. The relay 365 of the connector and the relay 330 115 of the distributing switch are then energized simultaneously and both attract their armatures. The energization of the test relay 365 causes the closure of the circuit of the ringing relay 376, which circuit includes the interrupter 364, so that the ringing nelay 376 is now alternately energized and del nergizcd.

In the system herein described, called lines test busy at the connector if the connection we between the positive pole of the exchange battery and the test wire of the called line is interrupted, as has already been explained with relation to contact 339 of the eff-normal switch 338. It will have been I noticed that the busy condition is removed in the case of a revertive call by the test wire 386 of the: desired line being re-connected by the contact 390 and through the winding of relay 330 to the positive pole of the battery at the same moment in which the test circuit, including the test relay 365 at the connector, is comp eted at the contact 113 by the relay 367. The contact arms 382, 383 of the connector are now in connection with the wires 387, 388, Fig. '1, leading to the distributing switch of the desired line.- The wire 388 leads to the resistance 391 and through the wire 104 to the limb 1 of the desired line. It also leads through a back contact 405 of the relay 331 and through the right-hand winding of the differential relay 392, front contact 116 of the rela 330 and through the line relay 326 to t e limb 1 of the desired line. The wire 387 leads-through the resistance 393 and the wire 105 to the limbi of the desired line, and it also leads throu h a back contact 162 of the relay 331 and through the left-hand winding of the differential relay 392, front contact 117 of relay 330, back contact 161, of relay331, line relay 327 to the limb 2 of the'desired line. The windings of the linerelays 326. and 327 are of high impedance so that the greater part of the ringing current flows through the resistances 391 and 393. At this juncture .it will be mentioned that the party line system disclosed herein is so arranged that all the selectors used in calling a party in the case of a, revertive call are released as soon as they are no longer required. Group selector Fig. 2 and the distributing switch, Fig. 1 of the calling line are reieasedat the moment when the connector Fig. 3 makes the revertive connection. The connector is released the moment the called station answers. The release of the group selector and distributing switch is effected by the deenergization of the line relay 327 which takes place after the last series of selecting impulses have affected line relay 326. At the moment when the final deenergization of the relay 327 takes place, due to the working of the impulse transmitter of the calling subscriber 320, the relay 367 is'energized in a manner already described by an impulse flowing through the wires 347, 355,

363, and at the same time an impulse is sent over the other limb of the talking circuit. This impulse flows from the positive pole of the battery through back contact 106 of line relay 327, front contact 107 of relay arm 348, talking wire 362, front contact of relay 367, (which relay is energized by 330i1 this relay being energized in ,series a current flowing from the." distributing 355, 363), relay 368 to the negative pole. The relay 368 now attracts its armatures and .connects the positive pole of the battery through the contact 112 and the wire 151- with the test wire 359 of the trunk ex.- tending between the connector and the switchover the lower talking wires 347, I

group selectors, This causes a current to flow through the release magnet 362 of the grou selector, the path of which maybe traced from the positive pole of the battery at the'connector, armature contact 112, wire 151, wire'359, contact arm 350, lowermost front contact of relay 353, wire 343, con-.

tact 395, release magnet 362, minus pole of ,the battery. This restores the group selector to its normal position. The deenergization of the line relay 327 also causes the energization of the relay 396 for'the purpose of stepping the contact arms of the distributing switch forward into their nor- 1 mal position. The circuit of relay 3% may be traced from the negative pole of the battery through contact 397 of theoif-normal switch 337, relay 396, wire 397 contact 398, contact 107, contact 106, positive pole. By attracting its armatures the relay. 396 'closes a circuit through the turning magnet of the distributing switch, which may .be traced as followsznegative pole of the battery, interrupter 336, front contact 400 of relay 396, turning magnet 334, front contact 115., of line relay 326, plus pole of the bat tery. In order to prevent the relay 3 96 from being dee-nergized prematurely by the attraction of the armatures of relay 327, which it will be remembered is only deenergized momentarily, a locking contact 401 is provided that-makes the relay 396 after it has once attracted its armatures dependent only on the contact 397 of the ofl-normal switch 337. The turning magnet 334 steps the contact arms 340, 341, 3420f the -distributing switch around until they reach their normal position, in which the otf-normal switches 337 338 assumethe positions shown in Fig.

1. The relay 396 is then deenergized and .the circuit of the turning magnet 334 opened so that the contact arms 340, 341, 342 are arrested. i

In order to make the party line appear engaged even though the contact 339 of the elf-normal switch 338 is closed, the current path from the private normal wire 386 through the relay 330 to the positive pole of the battery is interrupted b a relay 389 shortly before the off-normal switch 338 'assur'nes its normal position. The energizati'on of the relay 389 is effected by a'transitory closure of a contact 402 which takes place shortly before the contact arms 340, 341, 342 regain their normal position. At the moment of the closure of the contact 402, and when the line relays 326, 327 both attract their armatures due to the current flowing to the line, an impulse is sent from the positive pole of the battery through the contact 402, wire 152, front contact 153 of the line relay 326, wire 154, contact 155 of relay 327, wire 156, relay 389 to the negative pole of the battery. By the energization of the relay 389 the private normal wire 386 is disconnected at the contact 403 from the positive pole of the battery. The relay 389 closes a locking circuit for itself through armature 158 from the positive pole of the battery, through contact 108 of line relay 327, contact 158, winding of 389, negative pole. If another subscriber now attempts to call the busy partyline the test relay of the connector used for making the second call will not get a connection with the positive pole of the battery through the relay 330, and will therefore remain dele'nergized so that a second connection with the busy line will not take place. The group selector that was used for making the re- Vertive call is now in a condition to be used for other connections. The connector, however, is still in connection with the line of the calling and called party. The calling station receives current between the intervals in which ringing current is being sent out over the line from the battery 370, Fig. 3 through the upper Winding of the dilferential relay 372, back contact 118 of relay 374, back contact 404 of ringing relay 376,

contact arm 382, normal wire 388, back con tact 405 of relay 331, right hand. winding of differential relay 392, Fig. 1, front contact 116 of relay 330, back contact 160 of relay 331, relay 326, limb 1 of calling line, calling station 320, limb 2, relay 327, back contact 161 of relay 331, front contact 117 of relay 330, left hand winding of ditferential relay 392, back contact 162 of relay 331, normal wire 387, contact arm 383, back contact 405 of relay 37 6, back contact 119 of relay 374, lower winding of differential relay 372, positive pole of the battery 371. As the resistances 391 and 393 at the distributing switch form shunts about the right and left hand windings of the difierential relay 392, current will also How through these resistances. These resistances are so dimensioned as not to affect the working of the differential relay 392. strength flow through the two windings of the differential relays 372 and 392, these relays will not attract their a-rmatures; but as soon as the party at the called station 325 raises his receiver from the switchhook and in so doing momentarily earths one of the limbs of the line, the strength of the current flowing through the one winding of each of the differential rela s 392 and 372 will be increased so that both relays attract their armatures. On the relay 372 attracting its armature, the relay 374 is As long as currents of equal.

nor/mes energized, and this latter relay by opening the circuit of the ringing relay 376 causes the ringing current to be out 01f. 0n the energization of the relay 372 the circuits of the release magnets 381 of the ringing current connector and 369 of the connector are also -closed over the following path: positive pole of the battery, contact 406, front contact 165 of relay 368, release magnets 369 and 381, negative pole of the battery. The ringing current selector and'connector thereupon restore their contact ams 385 and 382, 383, 384 to their normal positions. The moment the connector reaches its normal position it interrupts the locking circuits of the relays 368, 366 and 374 at the contacts h, z and j by means of an olfnormal switch lc so that all parts belonging to the connector are restored to normal. The energization of the differential relay 392 at the distributing switch effects the closure of the circuit of the relay 331 by a current flowing from the negative pole of the battery through the front contact 407 of relay 392, front contact of relay 330, positive pole of the battery. "The circuit of the relay 330 was closed by connecting the wire 386 to the negative pole, of the battery at the connector and by simultaneously momentarily denergizing the relay 327 at the distributing switch of the calling subscribers line. When this circuit was opened the relay 330 W215 immediately energized again because in the meantime a new circuit had been established by the relay 389 which included the contact 407. y The relay 330, therefore, remains energized until the locking circuit of the relay 389 is opened at the finish of the conversation by the contact 108 of relay 327. By the energization of relay 331 the current supply circuit for the subscribers transmitters is shifted from the battery 370, 371 of the connector to the battery 323, 333 of the distributing switch. The armature contact springs of the relay 331 are so adjusted that during this shifting of connections no interruption of the current that flows through the relays 326, 327 takes place. The calling and called stations of the party line now receive the current supply for their transmitters from the battery 323, 333 of the distributing switch. The path of this current may be traced from the battery 323 through the resistance 329, connection 109, front contact 170 of relay 331, line relay 326, limb 1 of party line, transmitters of stations 320 and 325, limb 2 of party line, line relay 327, front contact 171, wire 110, resistance 332, back to battery 333. At the finish. of the conversation the subscribers replace. their receivers and thus open the circuit-including the line relays 326, 327, thus causin the armatures of these relays to retract. The locking circuit of the relay 389, including the'conta/ct 108 of line relay 327 and contact 158, and the locking gircuit of relay 330 including the contact 407 of relay 389, are now opened so that both relays allow their armatures to fall back. The relay 331 is also deprived of current the moment the contact 111 of relay 330 is opened. All parts belonging to the distributing switch are now restored totheir normal position.

In case a station on a party line calls a station connected to another party line the switching processes are the same as in-' the case of a revertive call up to the moment when the final non-selecting or changeover impulse is sent over the limb 2 of the called line. If the desired line is free the final deenergization of the relay 327 causes the energization of the test relay 365 of the connector and of the relay 330 of the desired line. The relay 330 in the distributing switch of the calling line is, however, not energized. Hence no current impulse will be sent through the upper limb 340,

' 354, 362 of the talking circuit to the connector simultaneously with the impulse that is caused to flow through the lower limb 341, 355, 363, and the relay 396 belonging to the distributing switch of the calling line remains deenergized so that the moving of the distributing switch into its normal position does not occur. As no current impulse flows over the upper limb of the talking circuit the relay 368 at the final selector is not energized and consequentlythe release of the group selector-which is caused in the case of a revertive call by connecting the positive pole through the agency of relay 368 to the test or release wire 359 does not take place. When the connector has been set onto the calling line and a current impulse is caused to fiow through the deenergization of the relay 327 over the wire 103 and through the lower limb 347, 363 of the talking circuit, and through the relay 367 of the final selector, the test relay 365 of the same and the relay 330 of the distributing switch belonging to the desired party line are energized by a current flowing from the negative pole of the battery at the connector through contact 113 of relay 367, winding of test relay 365, contact arm 384, test wire 386, contact 339 of off-normal switch belonging to the distributing switch of the desired line, upper back contact of relay 389, winding of relay 330 to the positive pole of the battery. The test relay 365 of the connector is then energized and switches the ringing relay 376 into the cir-.

cuit of an interrupter 364 so that this relay is intermittently energized and caused to connect. the ringing current leads 410, 411

to the contact arms 382, 383 of the connec tor. As the relay 330 of the selected party is open and-disconnects the turning magnet:

line is energized the contact 114, of the same 334 from the interrupter 336; thus the distributing switch cannot be started moving when the called party answers and causes his relay 326 to be energized. The ringing current sent out to the desired line flows, as previously described, principally through the resistances 391, 393. The line relays 326, 327 of the called line are connected during the intervals in which no ringing current flows to the battery 370, 371 at the connector by way of contacts 116, 117 oftherelay 330, windings of differential relay 392, back contacts 162, 405 of relay 331, normal wires 387, 388, contact arms 382, 383, contacts 404, 405, contacts 118, 119, windings of difierentialrelay 37 2. The moment the called subscriber raises his receiver from his switchhook this latter momentarily earths one or both sides of the party line and thus causes .the energization of. the differential, relays 372 at the connector and 392 at the distributing switch. The relay 372 at the connector then causes the energization of the relay 374, which latter opens the circuit of the ringingrelay 376. The relay 374, by attracting its armatures 118, 119 extends the calling subscribers talking circuit to the contact arms 382 and 383, and hence to the called line while disconnecting the differential relay 372 and the battery 370, 371. The energization of the relay 392 of the distributing switch closes the circuit of the relay 331, causing it to close its contacts 170, and 171, whereby the battery supplied to the called line is transferred from the battery at the connector to the battery 323, 333 at the distributing switch. The called line now receives its current supply from battery 323 through resistance 329, 'wire 109, front contact 170 of relay 331, this relay having closedalocking circuit for itself, through winding of relay 326, limb 1, of the desired line, called station, limb 2, line relay 327, front contact 171 of relay 331 wire 110, resistance 332, battery 333. ,By the currentflowing from the negative pole of the battery through the test relay 365 and test contact 384 of the connector through the test wire 386 and the relay 330, a drop of potential on the test wire 386 is caused and the busy condition of the line established;

if other connections are attempted by' other connectors the-test relay 365 of, these connectors would not receive sufficient current to energize them so thatthey would be prevented from making a connection. If the test relay of a connector is not'immediately excited on testing, the connector is restored at once to its normal position. The restoring of a connector in' the case of a busy connection takes place at the cessation of the final impulse sent from the distributing switch in the manner already described over the lowerlimb 347, 355, 363, to the connector. This impulse energizes the relay 367 and connects the negative pole of the battery through its contad 113 to the test relay 365; it also closes the circuit of a relay 366 which energized and closes av locking circuit for itself. hen the impulse over the lower limb of the talking circuit ceases the relay 367 is deenergized, and, in case the test relay 365 has not attracted its arma tures, closes a release circuit which may be traced from the positive pole oil the battery through the back contact 130, wire 131, upper front contact of relay 366, back contact 132 oi test relay 365, back contact of relay 363, to the release wire 151, 150, 355), and to the release magnets 369 and 381 of the connector and ringing current selector respectively. The release magnets 331, 369, of the ringing current selector and the connector, and the release magnet 362' of the group selector are thus caused. to restore their switches to normal. The calling station would cause the release of the distributing switch, Fig. 1, by replacing its receiver and causing the line relays to deenergize; the turning magnet of the distributing switch would then receive current from the negative pole of the battery through the interrupter 33o, wire 412, back contact 114:, wire 13?, contact 200 of relay 327, back contact 192 of relay 326, contact 201 of ell-normal switch, turning magnet 334., wire 202, contact 138 of oti normal switch 337, to the positive pole of the battery. The turning magnet now steps for ward the contact arms of the distributing switch until they reach their normal position, when the contact 138 is opened and the operation of the turning magnet stopped. It the wanted line is found idle and the connector establishes the connection, the re-' lease is eli'ected at the end of the conversation the momentthe called subscriber rcplaces his receiver on the switclrhook. Linc relays 326 and 327 are then deenergized and the positive pole of the battery with the test or release wire 386 over ljthe following path I-fro1n the positive pole of the battery to the lowermost back contact of relay 326, wire 133, uppermostback contact of line relay 327, wire 134., front contact 159, of relay 331, contact 339, test or release wire 386. As the wire 386 is connected"through the armature 135 with the test or release wire 359, and since the relcasemagnets 369 and 381 of the connector current selector respectively are connected to the wire 359 through the bacl: contact 136 of relay 368, thorelease magnets of all switches used for the connection are excited so that all the switches are restored to normal. The locking circuit of the relay 33' of the distributing switch belonging to the called subscriber ,is opened by the retraction of armature 111 of relay 330, the moment therelay 330 is denergized. This takes is connected If the lifting magnet --pablc of connection to five different and the ringing is tuned to respond place as soon as the connector is restored to normal, the current flowing through the private normal 386 being then interrupted. The resistance of the relay 330 is such, that the branch circuit leading through the same from the wire 386 to the positive pole of the battery will not supply suilicient current to energize the release magnets of the group selector, connector and ringing current selector. It the calling subscriber is the first to replace his receiver, the wire leading to the positive pole of fully explained below, also connected to the test or release Wire 140, and through brush 342, to wire 343 so as to energize all the re lease magnets, which are connected to the same. The contact arms 340, 341 and 342 of the distributing switch are stepped around into their normal. position by the turning magnet 334, which receives current from the negative pole of the battery through the interrupter 336, back contact 114 of relay 330, wire 137, back contact 200 of relay 327, back contact 192 of relay 326, contact 201 of oil normal switch 337 turning magnet 33%, wire 202, contact 138 of off-normal switch 337, to the positive pole of the battery. The turning magnet now receives impulses produced by the interrupter 336 and the contact arms of the distributing switch are stepped around until they reach their normal position in which the oil-normal switch 337 is opened. A moment before the distributing switch reaches its normal condition the contact 139 of the ofi normal switch 338 is closed and the test or release wire in the exchange is then connected to the positive pole of the battery over the following path z-positive pole, lowermost back contact of line relay 326, uppermost back contact of line relay 32?, wire 1 10, contact 139, test contact arm 342, test wires 343 and 359. The positive pole being connected with the test Wires, the release magnets 362', 369 and 381 will be energized and all the selec tors restored to normal.

, 313 of the connector is made dependent for its impulses on the ringing currentselector 312, shown in Fig. 6, ten different party lines could be. connected to the ten bank contact sets in the first horizontal contact row of the connector, each party line being then cakinds the battery is, as will be' of ringing current, the particular kind of 1 ringing current being determined by the position into which the contact arm of the ringing current selector has been moved. It with this arrangement a subscriber-wishes to connect himself to the fourth line in the first horizontal contact row of the connector, and it he wishes to call the station on this line, the bell of which to the current sent out by the ringing current s0urce'315, he 13a 1 connector.

will work his switch-controllingdevice in the same way as .if he desired a connection with line No. 54 of the connector. In other words, he first sends five impulses that shall have the effect of movin contact arms of the connector to the fi th row of contacts, and he then sends fourimpulses that usually have the effect of moving the contact arms on to the fifth setof contacts in the fifth group. With the arrangement shown in Fig. 6, however, the five impulsesthat usually cause the .contact arms to selectthe fifth row of contacts on the connector cause the contact arm 41.5 of the ringingcnrrent selector 312 to take five rotary steps, and to connect the ringing current source 315 to the ringing current lead 316 of the When the contact piece 317 on the contact arm 415 of the ringing current selector passes the contacts318, 319, the lifting magnet 313 of the connector receives a current impulse which causes the contact arms ofthe connector to be lifted 'to its first horizontal contact row. The four ensuing selecting impulses which flow through the turning magnet 377 then turn the contact arms, of a connectoruntil the fourth line in the first horizontal contact row is reached. The ringing relay 376 is, if the wanted line is free, nowenergized in the manner described with reference to 3 and the bell of the station No. 5 of line No. 14 of the connector is caused to ring. Should the callingsu'bscriber desire a conversation with the fourth station of line 28 of the connector he would, after havin sent in the impulses for the operation of t e-selectors preceding the connector, send in first nine' selecting impulses that flow through the turning magnet 418 of the ringing current selector 312 and then eight selecting impulses that flow through the turning magnet 377" of the connector. The nine impulses that flow through the turning magnet 418 of the ringing current selector cause the 'contactarm.

of the latter tomove around nine steps and to connect the ringing current source 314 7 319 and 419, 420 cause two impulsesto fiow nector, whereby the. contact arms of the latto the ringing current lead 316. The COII'.

tact piece 317 attached tothe contact arm- 415. in passing the pairs of contacts 318"and through the lifting magnet 313 of the conter' are lifted to the. second contact row the eight ensuing selecting impulses ,fiow' sub sequently through the turning magnet 377 of' the; connector, causing the contact arms. of the'sa-me to be moved to the eighthline on "the :second -contact row. ,The contactarms-of the connector will nowbe resting upon line number 28 of the connectorand the ringing current lead 316,0f the same will be connected to theringing current source 314. The bell of station No. ton line No. 28 is adapted to respond, to this in Fig. .5.

ringing current. If the stations connected to the ten lines represented by the ten contact sets in the first contact row are given the first fifty numbers of the 100 stations, the subscriber will unconsciously cause the proper kind of ringing current to be connected to the party line for ringing the desired station on that-line. With the arrangement just described only two rows of ten contacts each instead of ten rows would be required on the connector. Instead of two contact rows With ten s ts of bank con tacts each, ten contact. rows with two contact sets each could be used, in which case the turning magnet ofthe ringing current selector would be actuated by the last series of impulses, instead of. the second last series, and instead of lifting magnet 313 of the connector the turning magnet "377 would be connected "to the contact. 318 of the'ringing current selector.

One ringing current selector need not necessarily be provided for each connector, a small number of ringing current selectors as shown at 308, Fig. 5, may be provided fora large group of connectors 417. With this arrangement the moment a connector is seized by a group selector the contact arms of a, connector finder-310 attach themselves to the leads 418, 419, 420, leading to the connector, and thus extend the ringing cura rent lead 418 of the same to the contact arm 421 of a ringing current selector 308. This connection bet-ween the ringing current lead 418 of the connector and the ringing current selector is maintained until the station called by means of the connector responds. The ringing current selector is then released so that it may be used for supplying the ringing current to another connector. I In Fig. 5 only such parts of a connector are shown as are required to enable the switching functions to be understood, which take place in connecting a'ringing current selector 308 to one of a large number of connectors 417.

Generally two or three ringing current selectors-30,8 with the finders 310 belonging ten connectors 417. A separate set of wires 418, 419, 420 is provided for each connector,

and these are connected in multiple to the thereto would be sufficient for a group crbankcontacts of connector finders 310, 311.

The circuits of the connectcrs are arranged in theinanner shown m Fig. 3 except that insteadof the turningmagnet 380 Fig. 3, a

morefiillyf'described later through the agencyeofthe armature contact 151' of the .irlay. 432 is connected in parallel to the liftdifi'erential relay 429 that corresponds to the differential relay 372, Fig. 3, andis ex; cited" at the moment when thecalled subscriber raises his receiver from the switchhook. The party lines are connected to the connector in the manner illustrated in Fig. 7. The first party line is connected to the first five contacts of the first horizontal row, and the second to the next five contacts in the same row. In the second horizontal contact row two further party lines are each connected to five contacts in a similar manner. Theremaining eight'contact rows also each represent two party lines so that altogether twenty party lines are connected to the connector. It will now be assumed that a subscriber by sending impulses in the ordinary manner has extended his line to the connector 417, Fig. 5. If the" subscriber sends in impulses through the wire 435 and through the lifting magnet 433 for the purpose of lifting the contact arms 438, 439, 440 to the row of bank contacts in which the desired line is to be found, the first of these impulses will cause the energization of the relay 432. This relayimmediately closes a locking circuit for itself, which includes an armature contact 252 of the differential relay 429. While the contact arms 438, 439, 440 are being lifted by the impulses coming in from the subscriber, the

contact arms 441, 442, 443 of a connector finder 310 will have started hunting for the wires 418, 419, 420 belonging to-the connector 417. This is brought about in the following manner: By the energization of the relay 432 the negativepole of the battery is connected to the wire 444 which is common to all the connector finders. The relays 426 of all the connector finders 310,- 311, etc., are then energized and the turning magnets 427 of all the connector finders then receive impulses from an interrupter 425, whereupon the turning magnets ste their contact arms 441, 442, 443, around. 3 soon as the contact arms of a connector finder reach the "set of bank contacts connected to the wires 418, 419, 420 belonging to the connector 417, a circuit is closed as'follows:- from the positive pole of the battery through the test relay 428 of the connector finder that is first to find the trunk 418,

' 419, 420, through contact .arm443, wire 420,

contact 445 of rela 432; relay 434, to the negative pole of t e battery. The relays 428 and 434 then both attract their armatures. The relay 428 opens the 'steppin circuit, including the turning magnet 42 of the connector finder, and the relay 434 interrupts .the connection between the negative pole of the battery and the common wire 444 so that the relays 426 of all the connectorfinders 310, 311, etc., allow their arma-tures to fall back so as to stop their motion. The findingof the connector by a connector finder takes place in the interval bet-ween the moment of excitation of the relay 432 by the first of the second last series of impulses sent in by the subscriber to move the contact arms 438, 439, 440, of the connector to the desired group, and themoment' when the last series of impulses for operating the connector is sent. in by the subscriber. When the subscriber sends in the last series ofimpulses that flows through the turning magnet 437 and causes the connector to perform its unitsselecting function, this series of impulses also flows through the turning magnet 423 of the ringing current selector 308 over the following path :from the trunk wire 435 lead-. ing from the subscriber through the upper off-normal contact 450 that is closed at the commencement of the units-selecting operation of the connector, wire 419, contact arm .441, turning magnet 423, to the negative pole of thebattery. If five impulses-are sent through the turning magnet 437 of the connector the first impulse will move the contact. arms 438, 439, 440 on to thefi rst party line connected to the bank contacts of the connector. The four remaining impulses will not move the contact arms 438,

439, 440, off this first party line because thelatter. is connected to five successive contacts in the manner shown in Fig. 7. These four impulses serve to rotate the contact arm 421 of the connector 308 by'four more steps so that it will be moved on to the contact 451 that is connected to the fifth ringing current source V of the ringing ,current' selector. Thus the fifth ringing current source V is connected to the ringing current lead 418 of the connector over the following path: ringing current source V, contact 451, contact arm 421, condenser 422, contact arm 442, trunk wire 418 of the connector. By means previously described with reference to Fig. 3 the ringing current relay 431 is caused to alternately attract-and release its armatures so that the station on the party line, the bell of which is adapted to respond to the ringing current sent out bythe ringin ferential relay.429 is energized in the man..- ner already described and causes contact 151' to be closed and the contact 252 to be opened The closure of the contact 151 causes the energization of the release magnet 4240f the ringing current selector over the following path: from the positive pole of the battery, armature contact 151, wire 418, contact arm 442 of the connector finder, release ma-gnet 424, 'to the negative pole of the battery. The current through the release magnet 424'cau'ses the contact arm of the ringing current selector to berestored to its normal position; The openlng of the contact 252. unlocks the relay 432 of the current-source V, is called. When the cal ed station responds the d1fconnector so that this relay'is deenergized,

and in turn deenergizes therelay 4.34 of the connector and the test relay428 of: the connector finder.

The application of ringing current selectors of the kind described above is not limited to systems in which the current imscriber are stored up at the exchange in registers. \Vith a known type of such regis-- ters the current impulses are stored and subsequently imparted to the selectors at the desired intervals. When used in conjunction with such registering devices the-ringing current selectors would be so connected that they would be caused to select the suitable ringing current source for signaling to the desired station on a party line when the impulses are sent from the calling station to the registering devices. The operation of the selectors that establish the connection would take place when the impulses stored up in the registers are repeated or given out. It is obvious that the system could also be so arranged that both the ringing current selectors and the selectors for establishing the talking connection are operated when the impulses stored up in the registers are given out.

While I have shown and described a separate source for eachkind of signaling current, such a plurality of sources is not essential to my invention as it is obvious that current of diiierent strengths can be derived from the same battery through resistances or of different frequencies through interrupters. Even battery current of difierent polarities might in some cases. be used. I, therefore, wish it understood that I contemplate all such equivalents of the means shown, and that the expressions ringing current of different kinds, sources of current, and all similar expressions used in the claims are to be interpreted as intending all such equivalents.

I claim:

1. An automatic switching system comprising line selecting devices each having series of fixed contacts, movable contacts capable of being set on to any of said series Copies of this patent may be obtained for of fixed contacts and on to any contact of the said series, a series selecting magnet for moving said movable contacts to any of the said series of contacts, an individual selecting magnet for selecting any individual contact of a series, ringing current selectors fewer in number than the line selecting devices and capable of selecting several kinds of ringing current, and connecting switches for connecting the ringing current selectors to the line selecting devices.

2. An automatic switching system comprising line selecting devices each having series of fixed contacts, movable contacts capable of being set on to any of the said series of fixed contacts and on to any contact of the said series, a series selecting magnet for moving said movable contacts to any of the saidseries of contacts; an individual selecting magnet for selecting any individual contact of a series, ringing current selectors fewer in number than the line selecting del vices and'capable of selecting different k nds of ringing current, connecting switches for connecting the ringing current. selectors to the line selecting devices and means associated with each line selecting device for starting the operation of the said connectingswitches at the time during which a said se ries selecting magnet operates.

3. An automatic switching system comprising line selecting devices with magnets for setting same, a current supply source for energizing said magnets, subscribers lines,

subscribers stations, controlling devices for causing series of impulses to flow from said current supply source through the said mag nets, bells at the said stations adapted to respond to different kinds of ringing current, selectors fewer in number than lecting devices and capable of selecting different kinds of ringing current, electrical connections between said selecting devices and said selectors andmagnets for actuating said selectors that operate under the control of the same impulses ofthe said series of impulses as the said magnets for setting the line selecting devices.

In witness whereof, I hereunto subscribe my name this 27th day of Sept. A. 1)., 1912.

FRITZ ALDENDORFF.

Witnesses:

H. MENGER, H. TUoK SHERMAN.

Washington, D. G.

the said, se 

